Calculating Voltage Drop


When selecting a cable for a application it is important to consider what effect on the voltage the resistance of the cable itself will have. Most devices have a range of voltages that they can effectively operate within.


Icon Exclamation Mark LoxoneVoltage drop is not the only factor in deciding cable core thickness. You must also consider the load carrying capacity of the cable. Please refer to the standards of installation in which you operate under to select the correct cable for this in conjunction with that of voltage drop.

The voltage drop can be calculated using the following formula:

ΔU = I · R = I · ((2 · L · ρ) / A)

I … Current [A]
L … Cable Length [m]
A … Cable Cross-Section [mm²]
ΔU … Voltage Drop [V]
ρ … Material Specific Resistance [( Ω*m)/mm²]

ρ= 0.0172 (for Copper)